In a microwave-safe 4-cup measure combine chocolate pieces, butter, and milk. Microwave, uncovered, on 100 percent power (high) for 1 to 2-1/2 minutes or until soft enough to stir smooth, stirring once during cooking.

Gradually stir about half of the hot mixture into beaten egg yolk. Return to the 4-cup measure. Microwave, uncovered, about 1 minute or until bubbly, stirring after every 30 seconds.

Stir in liquor, liqueur, or orange juice. Cover and chill about 1 hour or until mixture is cool, evenly thick, and smooth, stirring occasionally.

Beat chocolate mixture with an electric mixer on medium speed about 2 minutes or until slightly fluffy and lighter in color. Cover and chill about 15 minutes or until mixture holds its shape.

Drop from a slightly rounded teaspoon measure onto a baking sheet lined with waxed paper. Cover and chill about 30 minutes or until firm. If desired, dip in melted chocolate; place in foil candy cups. Sprinkle with nuts, candy sprinkles, or coconut, or drizzle with melted white baking pieces. Or, instead of dipping, roll balls in nuts, candy sprinkles, or coconut. Makes 48 pieces (about 3/4 pound).

Up to 1 week ahead, make truffles. Place in an airtight container and store at room temperature.